System using radiation of far infrared ray for heat release

ABSTRACT

Provided is a system having a heat source unit, and a first heat releasing member arranged on the heat source unit or at a location near the heat source unit, to convert heat into a far infrared ray and radiate the far infrared ray. The provided system uses the heat releasing member formed of a material for converting heat into a far infrared ray and radiate the far infrared ray and vice versa, thus the heat is efficiently exhausted to the outside without increasing the inner temperature of the unit.

CROSS-REFERENCE TO RELATED PATENT APPLICATION

This application claims the benefit under 35 U.S.C. §119(a) of Korean Patent Application Nos. 10-2004-0085090, filed on Oct. 23, 2004, and 10-2005-0000221, filed on Jan. 13, 2005, in the Korean Intellectual Property Office, the entire disclosures of both of which are hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a system having a heat source unit. More particularly, the present invention relates to a system for releasing heat generated at a heat source unit by using radiation of a far infrared ray.

2. Description of the Related Art

In general, an optical scanning unit, such as a laser scanning unit (LSU) is used in an image forming apparatus for reproducing images on sheets such as a copy machine, a printer, a facsimile machine, and the like. An optical scanning unit forms electrostatic latent images by scanning a beam emitted from a light source, such as a laser diode, based on image signals to a photoreceptor medium of an image forming apparatus by using a rotating polygonal mirror, which is rotated by a driving motor.

Images are reproduced by transferring latent images formed on the photoreceptor medium to a medium, such as paper. Generally, optical elements forming the optical scanning unit are assembled on one frame.

When an image forming apparatus, for example, a laser printer, outputs images for a long time, the inner temperature of an optical scanning unit increases due to heat from circuit units of a semiconductor laser and a driving motor for rotating polygonal mirror, heat generated by friction between air and the rotating polygonal mirror, and heat from a printer main body. When the inner temperature of the optical scanning unit increases, a frame and members for fixing lenses are slightly transformed. Thus, the alignment of optical elements may be deviated and an optical performance may be deteriorated by the changes in the inner refractive indexes and curvatures of lenses. More specifically, the changes in the inner refractive indexes and curvatures of the lenses cause the change in a focus distance, the increase in a beam diameter on an image plane, and the generation of vertical stain patterns.

In a conventional method, a metal frame, such as aluminum, having an excellent thermal conductivity is used or a heat sink is used to emit the heat to the outside through conduction and convection, in order to reduce the increase in the temperature of the image forming apparatus.

Japanese Laid-open Patent No. 2001-142023 discloses an optical scanning unit having an aluminum frame and sealing a rotating polygonal mirror and driving motor unit for preventing noise of the driving motor. In this case, a heat sink, which has heat sink fins connected from the inside of the optical scanning unit to the outside of the optical scanning unit, is used at a portion generating heat in order to release heat from the sealed area.

However, the heat sink fins connected from the inside to the outside of the optical scanning unit limits the reduction of the size of an image forming apparatus, such as a laser printer or a copy machine.

Such a method of using a heat sink or a cooling fan limits the ability to reduce the size of an apparatus and also increases the cost of the apparatus.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide a system for releasing heat to the outside without increasing the inner temperature of the system by converting the heat generated from a heat source into a far infrared ray and releasing the far infrared ray.

According to an aspect of the present invention, there is provided a system comprising a heat source unit, and a first heat releasing member arranged on the heat source unit or at a location near the heat source unit for converting heat into an infrared ray and radiating the far infrared ray.

The system may further comprise a housing containing the heat source unit, wherein an air layer is disposed between the housing and the heat source unit or the heat source unit contacts the housing.

The system may further comprise a second heat releasing member arranged on an inner wall of the housing for converting the far infrared ray into heat.

The system may further comprise a third heat releasing member arranged on an outer wall of the housing for converting heat, which is converted by the second heat releasing member and conducted through the housing, into the far infrared ray and radiating the ray to the outside.

The system may further comprise a fourth heat releasing member arranged on an outer wall of the housing near the heat source unit for converting the heat, which is generated by the heat source unit and conducted through the housing, into the far infrared ray and radiating the far infrared ray.

The first through fourth heat releasing members are preferably ceramic.

The system may be any one of an optical scanning unit, an image forming apparatus having an optical scanning unit, an image forming apparatus having a fixing unit, and an image forming apparatus having an optical scanning unit and a fixing unit.

According to another aspect of the present invention, there is provided an optical scanning unit comprising a beam deflector unit including a beam deflector for deflecting and scanning a light beam and a driving motor for rotating the beam deflector at a high speed. An optical unit includes a light source and an image forming optical system forms images from the deflected light beam. The light beam is transmitted from the light source to the beam deflector and scanned by the beam deflector unit. A main frame contains the beam deflector unit and the optical unit. A sub-frame surrounds the beam deflector unit to reduce noise generated by the beam deflector unit in the main frame and has a passage for processing the light beam between the beam deflector unit and the optical unit. A first heat releasing member is disposed on an outer surface of the sub-frame, and converts heat generated in the sub-frame into a far infrared ray and radiates the far infrared ray.

The optical scanning unit may further comprise a second heat releasing member arranged on an inner surface of the main frame to convert the far infrared ray, which is radiated to the inside of the main frame by the first heat releasing member, into heat. A third heat releasing member can be disposed on an outer surface of the main frame to convert heat which is conducted through the main frame into a far infrared ray and radiate the ray to the outside.

The first through third heat releasing members are preferably ceramic.

The optical scanning unit may further comprise a barrier wall spatially separating the optical unit from the beam deflector unit and the sub-frame in the main frame. The barrier wall preferably has a passage for processing the light beam.

At least one portion of at least one of the main frame and the sub-frame may be formed of a heat conductive plastic having higher heat conductivity than a general plastic.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which:

FIG. 1 is a sectional view illustrating a system to which a heat releasing technology according to an embodiment of the present invention is applied;

FIG. 2 is a sectional view illustrating a heat releasing process from a second heat releasing member and a third heat releasing member of FIG. 1 according to an embodiment of the present invention;

FIG. 3 is a plane view of a system model explaining a heat releasing effect by radiation of a far infrared ray;

FIG. 4 is a graph illustrating temperatures measured at portions of the system model of FIG. 3, and temperatures measured in a conventional model not using ceramic;

FIG. 5 is a sectional view of an electrophotographic image forming apparatus according to an embodiment of the present invention;

FIG. 6 is a perspective view of an example of the optical configurations of an optical scanning unit;

FIG. 7 is a sectional view of an optical scanning unit having a heat releasing member according to an embodiment of the present invention, wherein the heat releasing member is formed to radiate heat generated from a polygonal mirror as a far infrared ray;

FIG. 8 is a sectional view of an optical scanning unit according to another embodiment of the present invention;

FIG. 9 is a sectional view of an optical scanning unit according to another embodiment of the present invention; and

FIG. 10 is a sectional view of an optical scanning unit according to another embodiment of the present invention.

Throughout the drawings, like reference numbers should be understood to refer to like elements, features and structures.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

FIG. 1 is a sectional view illustrating a system to which a heat releasing technology according to an embodiment of the present invention is applied. Referring to FIG. 1, the system includes a housing 1, heat source units 10 and 30 installed in the housing 1, and first heat releasing members 15, 17, and 35 located on the heat source units 10 and 30 or a location near the heat source units 10 and 30 to convert heat into a far infrared ray and radiate the far infrared ray.

In the area A of FIG. 1, the heat source unit 10 is separated from one surface of the housing 1, thus an air layer is disposed between the heat source unit 10 and the housing 1. In the case of an optical scanning unit of an image forming apparatus, a polygonal mirror acts as the heat source unit 10. In the area B of FIG. 1, the heat source unit 30 is attached to a surface of the housing 1. In the case of the optical scanning unit of the image forming apparatus, a light source for generating and irradiating a laser beam acts as the heat source unit 30. Of course, these are merely examples. In other cases, a polygonal mirror may be combined with the housing in the structure shown in the area B of FIG. 1, and the light source may be combined with the housing in the structure shown in the area A of FIG. 1. When the heat source units 10 and 30 are referred to be attached to the housing 1, the heat source units 10 and 30 may be directly attached to the housing 1 or a predetermined member may be interposed between the heat source units 10 and 30 and the housing 1 to operate as a passage for conducting a portion of the heat generated by the heat source units 10 and 30 to the housing 1.

A system including the heat source units 10 and 30 may have the structure shown in the area A of FIG. 1 the structure shown in the area B of FIG. 1, or both. In other words, a system including the heat source units 10 and 30 may have at least one of a structure where an air layer is disposed between the heat source unit 10 and the housing 1 and a structure where the heat source unit 30 is in contact with the housing 1.

The housing 1 is preferably formed of a metal having excellent conductivity, such as aluminum, for example. At the inside of the housing 1, the first heat releasing members 15, 17, and 35 convert the heat generated by the heat source units 10 and 30 into a far infrared ray and radiate the far infrared ray.

The heat generated by the heat source units 10 and 30 is conducted to the first heat releasing members 15, 17, and 35. The first heat releasing members 15, 17, and 35 may be formed on predetermined surfaces of the heat source units 10 and 30 or on surfaces of a predetermined member contacting the heat source units 10 and 30.

In the case of the area A of FIG. 1 where the heat source unit 10 is separated from the bottom of the housing 1 and an air layer is disposed between the heat source unit 10 and the housing 1, the first heat releasing members 15 and 17 may be formed on a surface of the heat source unit 10 facing a bottom 1 a of the housing 1 and on at least one other surface. In FIG. 1, the first heat releasing members 15 and 17 are formed on the upper surface and the lower surface of the heat source unit 10. In this case, the heat generated by the heat source unit 10 is converted into a far infrared ray by the first heat releasing units 15 and 17 and radiated to the inner space of the housing 1.

In the case of the area B of FIG. 1 where the heat source unit 30 is attached to one surface of the housing 1, for example, the bottom 1 a of the housing 1, the first heat releasing member 35 is formed on at least one surface of the heat source unit 30 not facing the bottom 1 a of the housing 1. In this case, a portion of the heat generated by the heat source unit 30 and conducted to the first heat releasing member 35 is converted into a far infrared ray by the first heat releasing member 35 and radiated to the inner space of the housing 1 while the other portion of the heat is directly conducted to the housing 1.

A system according to an embodiment of the present invention may further include second heat releasing members 41, 51, and 61 on the inner surface of the housing 1 in order to absorb the far infrared ray radiated within the housing and convert the far infrared ray into heat. This heat is conducted through the housing 1. In addition, a system according to an embodiment of the present invention may further include third heat releasing members 45, 55, and 65 on the outer surface of the housing 1 in order to convert heat conducted through the housing 1 into a far infrared ray and radiate the far infrared ray to the outside of the housing 1.

In the case of the area A of FIG. 1 where an air layer is disposed between the heat source unit 10 and the bottom la of the housing 1, the second heat releasing units 41 and 51 are formed on the bottom 1 a of the housing under the heat source unit 10 and on the inner surface of the housing 1 above the heat source unit 10, respectively, and the third heat releasing units 45 and 55 are formed on the corresponding outer surfaces of the housing 1, respectively.

In the case of the area B of FIG. 1 where the heat source unit 30 is attached to the housing 1, the second heat releasing unit 61 is formed on the inner surface of the housing 1 facing the heat source unit 30, and the third heat releasing unit 65 is formed on the corresponding outer surface of the housing 1.

In addition, in the case of the area B of FIG. 1 where the heat source unit 30 is attached to the housing 1, a fourth heat releasing unit 75 for absorbing the heat conducted through the housing 1 and converting heat into a far infrared ray may be formed on the outer surface of the housing 1 corresponding to the heat source unit 30, in order to effectively release the heat generated by the heat source unit 30 and conducted to the outside through the housing 1.

When the second heat releasing members 41, 51, and 61 are arranged on the inner surface of the housing 1, the light energy, in other words, the far infrared ray, radiated from the first heat releasing members 15, 17 and 35 can be absorbed effectively and converted into heat to be conducted through the housing 1. In addition, when the third heat releasing members 45, 55, and 65 or the fourth heat releasing member 75 are arranged on the outside of the housing 1, a far infrared ray which is not harmful to humans is radiated to the outside of the system. Thus the increase of temperature outside of the system is prevented and the system is safe.

FIG. 2 is a sectional view illustrating a heat releasing process by the second heat releasing members 41, 51, and 61 and the third heat releasing members 45, 55, and 65. Referring to FIG. 2, the far infrared ray radiated to the inner space of the housing 1 is absorbed by the second heat releasing members 41, 51, and 61 and converted into heat energy to be conducted toward the outer wall of the housing 1. The conducted heat is converted into the light energy, in other words, a far infrared ray, by the third heat releasing members 45, 55, and 65 and radiated to the outside of the system.

Accordingly, the heat generated in the system is released to the outside of the system without increasing the inner temperature of the system, and the increase of the temperature at the outside of the system can be prevented due to far infrared ray radiation by the heat releasing members attached on the outer wall of the housing 1.

The heat releasing members used in a system according to an embodiment of the present invention are preferably formed by attaching a thin ceramic sheet having a characteristic of converting heat into a far infrared ray and radiating the far infrared ray to a target object or coating a paint including ceramic on the target object.

In this case, the target object may be the heat source units 10 and 30, a predetermined member located near the heat source units 10 and 30, or the inner and/or outer walls of the housing 1 including the heat source units 10 and 30.

On the other hand, when the surface area of the heat source units 10 and 30 are small, the surface area of the heat source units 10 and 30 may be increased by adhering a metal sheet, such as an aluminum sheet, on the surfaces of the heat source units 10 and 30, and the ceramic material may be attached or coated to the metal sheet. As a result, a heat releasing effect can be improved.

As described above, a system according to an embodiment of the present invention uses a material for converting heat into a far infrared ray for radiating the far infrared ray and absorbing a far infrared ray for converting the absorbed far infrared ray into heat. As an example, ceramic can be selected as a heat releasing member. Thus the increase of temperature inside the system can be prevented.

In other words, a far infrared ray is an electromagnetic wave and is transmitted at the speed of light. Thus the transmitting loss rate is low and the heat efficiency is good. In embodiments of the present invention, heat efficiency refers to heat transmission efficiency. In this case, due to the electromagnetic wave property of a far infrared ray, the ray transmits heat while not heating the temperature of the inner air of the system, which includes the heat source units. Therefore, an increase of temperature inside the system can be prevented. An ideal black body having a radiation rate of 100% does not exist in nature. However, heat radiation efficiency can be improved by using a material having characteristics as close as possible to that of an ideal black body.

A material having a high radiation rate of electromagnetic waves, and in particular far infrared rays, absorbs the far infrared ray well. A representative example of such a material is ceramic. The radiation rates of several materials are shown in Table 1. TABLE 1 ideal black metal (Al, body Cu, etc.) plastic ceramic heat radiation rate 1 0.05-0.1 0.6-0.85 0.9-0.95

Referring to Table 1, ceramic has a high heat radiation rate, which is close to that of an ideal black body.

Heat is transmitted by conduction, convection, and radiation. The conventional heat releasing method using a heat sink for reducing the temperature of a predetermined unit uses conduction and convection. On the other hand, the system according to an embodiment of the present invention transmits heat using a far infrared ray, which corresponds to radiation.

FIG. 3 is a plane view of an exemplary system model for explaining the heat release effect by using far infrared ray radiation. FIG. 4 is a graph illustrating the temperatures measured at several positions of the system model of FIG. 3 in comparison with the temperatures measured at several positions of a system which does not use ceramic.

In FIG. 3, reference numeral 80 denotes a heat source unit, reference numeral 90 denotes a housing including the heat source unit, reference numeral 85 denotes a ceramic sheet surrounding the heat source unit, and reference numerals 91 and 95 denote an inner ceramic sheet and an outer ceramic sheet attached to the inner wall and the outer wall of the housing 90, respectively. In addition, the housing 90 is formed of aluminum.

Heat generated by the heat source unit 80 is conducted to the ceramic sheet 85 as a heat releasing member, and the ceramic sheet 85 absorbs the heat to radiate a far infrared ray. The inner ceramic sheet 91 absorbs the radiated far infrared ray and converts the far infrared ray into heat. In addition, heat is conducted by the housing 90 to the outer ceramic sheet 95. Then, the outer ceramic sheet 95 absorbs the heat, converts the heat into a far infrared ray, and radiates the far infrared ray.

The graph of FIG. 4 illustrates the temperature T1 measured on the heat source unit 80, the temperature T2 measured in the inner space of the housing 90, and the temperature T3 measured at the outside of the housing 90, in such a system model, before and after attachment of the ceramic sheets 85, 91 and 95.

Referring to FIG. 4, the temperature Ti measured on the heat source unit 80, which was about 142° C. before attaching the ceramic sheets 85, 91, and 95, is lowered to about 110° C. after attaching the ceramic sheets 85, 91, and 95. The temperature T2 measured in the housing 90, which was about 60° C. before attaching the ceramic sheets 85, 91, and 95, is lowered to about 50° after attaching the ceramic sheets 85, 91, and 95. In addition, the temperature T3 measured at the outside of the housing 90, which was about 43° C. before attaching the ceramic sheets 85, 91, and 95, is lowered to about 40° C. after attaching the ceramic sheets 85, 91, and 95.

According to the graph of FIG. 4, when a heat releasing member, which converts heat into a far infrared ray and radiates the far infrared ray and vice versa, is used, the temperature of a heat source unit is lowered while reducing the temperature of the inside of a system. Furthermore, it is helpful in lowering the temperature outside of the system.

Accordingly, the heat can be efficiently released to the outside of the system without increasing the inner temperature of the system at a low cost by arranging only heat releasing members at predetermined locations of the system by attaching ceramic sheets or coating ceramic material, without substantially changing the structure of the system. In addition, the far infrared ray, which is safe to human bodies, is radiated to the outside of the system, instead of heat or hot air. Thus, the system can be applied to avoid inclureasing temperature outside of a device, to save energy, and to improve safety.

Examples of a system using a far infrared ray radiation according to the present invention include an optical scanning unit, a fixing unit, and an electro-photographic image forming apparatus, such as a printer, among others.

An electro-photographic image forming apparatus including an optical scanning unit and a fixing unit will now be described as an exemplary embodiment of the system using far infrared ray radiation.

FIG. 5 is a sectional view of an electro-photographic image forming apparatus according to an embodiment of the present invention.

Referring to FIG. 5, the electro-photographic image forming apparatus 100 according to an embodiment of the present invention includes a photoreceptor medium, such as a photoreceptor drum 120, a developer 130, an intermediate transfer body 150, a transfer roller 152, a fixing unit 160, and a discharge unit 180 that are surrounded by a case 101.

A cassette 110 in which printing sheets S are stored is removably installed to a main body at a lower part of the image forming apparatus 100. A pickup roller 111 for picking up the printing sheets S one at a time is installed at the upper portion of the cassette 110. Images are formed on the printing sheets S, which are picked up by the pickup roller 111 and transferred through a sheet transfer path 112. The printing sheets S on which the images are formed are discharged to a discharge tray 171.

The photoreceptor drum 120 is preferably formed by forming photoconductive material on a metal drum. The optical scanning unit 140 radiates a beam corresponding to image signals onto the photoreceptor drum 120, which is charged to have a uniform electric potential, to form latent electrostatic images.

Reference numeral 122 denotes a charge roller, which charges the photoreceptor drum 120 to a uniform electric potential. The charge roller 122 supplies charge to the photoreceptor drum 120 by rotating in a contact or non-contact state to the external circumference of the photoreceptor drum 120. Thus, the external circumference of the photoreceptor drum 120 is charged to a uniform electric potential.

Reference numeral 121 denotes a discharger for discharging the charges remaining on the external circumference of the photoreceptor drum 120 before a charge process. The discharger 121 radiates light of a predetermined intensity to the external circumference of the photoreceptor drum 120 to eliminate the charge remaining on the photoreceptor drum 120.

The developer 130 typically has four toner cartridges for storing solid powder toners of black K, yellow Y, magenta M, and cyan C. The toners stored in the four toner cartridges are supplied to the latent electrostatic images formed on the photoreceptor drum 120 to convert the latent electrostatic images into toner images.

The intermediate transfer body 150 transfers the toner images from the photoreceptor drum 120 to the printing sheets S using a transfer belt.

The toner images of cyan C, magenta M, yellow Y, and black K formed on the photoreceptor drum 120 are sequentially transferred and overlapped on the intermediate transfer body 150 in order to form color toner images. The intermediate transfer body 150 typically uses a transfer belt.

The transfer roller 152 is installed to face and contact to the intermediate transfer body 150. While the color toner images are transferred from the photoreceptor drum 120 to the intermediate transfer body 150, the transfer roller 152 is separated from the intermediate transfer body 150. When the transfer of the color toner images to the intermediate transfer body 150 is completed, the transfer roller 152 contacts the intermediate transfer body 150 at a predetermined pressure in order to transfer the color toner images to the printing sheet S.

The fixing unit 160 supplies heat and pressure to the printing sheet S to which the toner images are transferred in order to fix the toner images on the printing sheet S. Then, the printing sheet S is discharged to the outside through a discharge roller 170 and loaded on a discharge tray 171.

The discharge unit 180 for discharging heat from the inside of the main body of the image forming apparatus 100 to the outside of the main body is formed of an opening at one side of the main body and a fan, which is installed to the main body. During rotation of the fan, air from the inside of the main body is discharged to the outside through the opening.

In such an electrophotographic image forming apparatus 100, the fixing unit 160 may correspond to a heat source unit.

Thus, a ceramic heat releasing member 165 for converting heat into a far infrared ray may be arranged on the fixing unit 160. In addition, a heat releasing member 167 may be arranged on the inner wall of the case 101, in order to efficiently discharge the far infrared ray, which is radiated from the heat releasing member 165, to the outside of the image forming apparatus 100. In addition, a heat releasing member 169 may be arranged on the outside of the case 101 to convert heat from the case 101 into a far infrared ray to be radiated to the outside of the apparatus 100.

When the heat releasing members 167 and 169 are arranged, the heat releasing member 167 converts the far infrared ray radiated from the heat releasing member 165, which is arranged on the fixing unit 160, into heat, and the heat is conducted to the heat releasing member 169 through the case 101. Thereafter, the heat releasing member 169 converts the heat into a far infrared ray and radiates the far infrared ray to the outside.

In FIG. 5, the heat releasing member 165 is preferably formed to completely surround the fixing unit 160, and the heat releasing members 167 and 169 are formed on portions of the inner wall and the outer wall of the case 101 near the fixing unit 160. However, the locations and the areas of the heat releasing members 165, 167, and 169 can vary according to design.

On the other hand, the temperature of the optical scanning unit 140 may be increased by heat due to the friction between air and a beam deflector, for example, a rotating polygonal mirror rotating in high speed, the heat from a circuit unit of a driving motor for rotating the rotating polygonal mirror, the heat from a laser diode used as a light source and a driving circuit unit therefore, and the heat transmitted from the main body of the image forming apparatus. Thus, it is preferable that at least one heat releasing member using far infrared ray radiation is used in the optical scanning unit 140.

FIG. 6 is a perspective view of an optical structure of the optical scanning unit according to an embodiment of the present invention.

Referring to FIG. 6, an optical scanning unit includes a light source 220 for generating a laser light beam, a beam deflector 230 for deflecting the light beam input from the light source 220, and a reflection mirror 250 for reflecting the light beam deflected on the beam deflector 230 toward a photoreceptor medium, such as a photoreceptor drum 120. In addition, the optical scanning unit further includes an image forming optical system for forming the light beam deflected by the beam deflector 230 on the photoreceptor drum, for example, an f-θ lens 240. Furthermore, the optical scanning unit includes a detection mirror 260 for reflecting a portion of the light beam reflected by the beam deflector 230 and a detection sensor 270 for receiving the light beam reflected from the detection mirror 260 to detect synchronization.

Reference numeral 221 of FIG. 6 denotes a collimating lens for converting the divergence beam output from the light source 220 into a convergence beam or a parallel beam, and reference numeral 225 denotes a cylinder lens for focusing the beam input from the light source 220 in a sub-scanning direction.

The light source 220 is modulated to selectively radiate the beam to portions of the photoreceptor drum 120 on which latent images will be formed. A laser diode can be used as the light source 220.

The beam deflector 230 deflects and scans the light beam emitted from the light source 220 in a main scanning direction of the photoreceptor drum 120. A polygonal mirror unit can be used as the beam deflector 230 as shown in FIG. 6. The polygonal mirror unit includes a driving source 235 such as a driving motor, and a polygonal mirror 231 installed on a rotating axis of the driving source 235. Reference numeral 233 of FIG. 6 denotes a circuit unit of the driving motor 235. The polygonal mirror 231 includes a plurality of mirrors formed on sidewalls for reflecting the incident light beam. The polygonal mirror is rotated to deflect and scan the incident light beam.

The f-θ lens 240 compensates the beam deflected by the beam deflector 230 by different magnifications for the main scanning direction and the sub-scanning direction and focuses the beam on the photoreceptor drum 120. Here, the sub-scanning direction refers to the rotation direction of the photoreceptor drum 120, and the main scanning direction denotes the axis direction of the photoreceptor drum 120, in other words, the scanning direction of the light beam through the beam reflector 230.

The reflection mirror 250 reflects the beam input from the f-θ lens 240 toward a photoreceptor medium, such as the photoreceptor drum 210.

In this case, the internal temperature of the optical scanning unit may be increased by heat due to a number of factors including the friction between air and the polygonal mirror 231 rotating in high speed, the heat from the circuit unit 233 of the driving motor 235 for rotating the polygonal mirror 231, the heat from the circuit unit (not shown) for driving the light source 220, and the heat transmitted from the main body of the image forming apparatus. Thus, it is preferable for a heat releasing member using far infrared ray radiation to be applied to the optical scanning unit.

The optical scanning unit can be formed as a single unit by installing the elements in a housing 280, as shown in FIG. 7. Referring to FIG. 7, an optical scanning unit according to an embodiment of the present invention includes heat releasing members 15, 17, 41, and 45 to convert heat from the polygonal mirror unit 230 into a far infrared ray and to radiate the far infrared ray.

In the case where an air layer exists between the polygonal mirror unit 230 and the bottom of the housing 280 as shown in FIG. 7, the first heat releasing members 15 and 17 are arranged on and under a polygonal mirror 231, respectively. In addition, the second heat releasing member 41 is arranged on the inside bottom of the housing 280, and the third heat releasing member 45 is arranged on a corresponding external surface of the housing 280. In this case, the functions of the first through third heat releasing members 15, 17, 41, and 45 are substantially the same as those of the first through third heat releasing members shown in the area A of FIG. 1. Thus, the same reference numerals as FIG. 1 are used in FIG. 7 and the descriptions thereof are omitted.

The polygonal mirror unit 230 may also be directly installed on the housing 280 without an air layer disposed between the polygonal mirror unit 230 and the housing 280. In this case, the heat releasing members are installed as shown in the area B of FIG. 1.

The optical scanning unit of FIG. 7 releases the heat generated by the polygonal mirror unit 230 to the outside of the housing 280 as a far infrared ray without increasing the internal temperature of the optical scanning unit. Such a heat releasing structure can be applied to a system for releasing the heat generated from other heat sources, such as a light source and/or a circuit unit for driving the light source, to the outside of the housing 280 as a far infrared ray.

In this case, when the system shown in FIG. 1 is referred to as an optical scanning unit, the housing 1 of FIG. 1 corresponds to the housing 280 of FIG. 7 in which elements of the optical scanning unit are installed, and the heat source unit corresponds to at least one of the polygonal mirror unit 230, a circuit unit 233 thereof (FIG. 6), the light source 220, and a circuit unit thereof.

As described above, when the heat releasing technique according to an embodiment of the present invention is applied to the optical scanning unit, deterioration of the optical characteristics, such as a change in a focal length, due to the increase in the internal temperature of the optical scanning unit can be substantially prevented.

In other words, when the internal temperature of the optical scanning unit is increased, the focal length of lenses are changed. In order to respond to the deterioration of the optical characteristics in conventional systems, a liquid collimating lens or a diffractive optical element was used, a zooming method by using a cam apparatus was used, or the internal temperature of the optical scanning unit was lowered by installing a heat sink or a cooling fan. However, such methods complicate the optical system and make it difficult to reduce the size of the optical apparatus, thereby increasing the manufacturing costs.

However, when a heat releasing technique according to an embodiment of the present invention is applied to an optical scanning unit, the heat can be efficiently exhausted to the outside of the optical scanning unit without increasing in the internal temperature of the optical scanning unit, and while minimizing changes in the structure of the optical scanning unit and at a lower cost. Accordingly, deterioration of the optical characteristics, such as a change in the focal length, can be substantially prevented.

The electro-photographic image forming apparatus shown in FIG. 5 can include the optical scanning unit of FIG. 7 as the optical scanning unit. In this case, heat releasing members (not shown) may be further arranged on the inner and outer walls of the housing 101, in order to radiate a far infrared ray radiated from the optical scanning unit to the housing 101, through the housing, and to the outside of the image forming apparatus 100.

FIG. 8 is a sectional view of an optical scanning unit according to another embodiment of the present invention. The optical scanning unit has substantially the same optical structure as the optical structure of the optical scanning unit of FIG. 6.

Referring to FIGS. 6 and 8, the optical scanning unit according to an embodiment of the present invention includes a polygonal mirror unit 230, an optical unit 500 having a light source 220 and an image forming optical system, a main frame 400 containing the beam deflector unit 230 and the optical unit 500, a sub-frame 440 for sealing the beam deflector unit 230 to reduce a noise from the beam deflector unit 230 in the main frame 400, and a first heat releasing member 450 arranged on an outer surface of the sub-frame 440. In addition, the optical scanning unit according to the second embodiment of the present invention may further include second and third heat releasing members 470 and 490 on the inner and outer surfaces of the main frame 400.

The optical system of the optical scanning unit according to the second embodiment of the present invention may be formed of a polygonal mirror 231 of the beam deflector unit 230 and the optical unit 500.

The optical unit 500 is formed of the light source 220 for generating a light beam, for example, a laser light beam, and a reflection mirror 450 for reflecting the light beam input from the light source 220 and deflected on the polygonal mirror unit 230 toward a photoreceptor medium, for example, a photoreceptor drum 120. In addition, the optical unit 500 further include an image forming optical system, for example, an f-θ lens 440, for forming the light beam deflected by the polygonal mirror unit 230 on the photoreceptor drum 120. Furthermore, the optical unit 500 may further include a detection mirror 460 for reflecting a portion of the light beam reflected from the polygonal mirror 231 and a detection sensor 470 for receiving the light beam reflected from the detection mirror 460 to detect synchronization. A collimating lens 221 converts the divergence beam output from the light source 220 into a convergence beam or a parallel beam. A cylinder lens 225 focuses the beam input from the light source 220 in a sub-scanning direction.

The internal temperature of such the optical scanning unit as above-described may be increased by heat due to the friction between air and the polygonal mirror 231 due to rotation in high speed, the heat from the driving motor 235 for rotating the polygonal mirror 231 and the circuit unit 433 thereof, and the heat transmitted from the main body of the image forming apparatus. In addition, the light source 220 and the circuit unit (not shown) for driving the light source 220 may increase the internal temperature of the optical scanning unit.

The polygonal mirror unit 230 and the optical unit 500 are installed on a bottom 415 of the main frame 400. The main frame 400 includes a cover 413, which is removable from a sidewall 411, at the upper portion. When the cover 413 is closed after the elements of the optical scanning unit are installed, the main frame 400 is sealed in order to prevent the contamination of the elements of the optical scanning unit.

The main frame 400 is formed of a plastic, more preferably, a heat conductive plastic having excellent heat conductivity. The heat conductive plastic has better heat conductivity compared to a general plastic by about 100 times. Such a heat conductive plastic can be substituted for a metal in heat conductivity point of view. The main frame 400 can be formed by a plastic molding process. In other words, the bottom 415 and the sidewall 411 of the main frame 400 may be formed by a molding process, and the cover 413 of the main frame can be formed by a separate molding process.

The sub-frame 440 is formed to surround the polygonal mirror unit 230 in the main frame 400 in order to-reduce the noise from the polygonal mirror unit 230. The sub-frame 440 includes a passage 435 for propagating the light beam between the optical unit 500 and the polygonal mirror unit 230. The passage 435 can be an open space or a transparent window which allows the light beam to penetrate. The passage 435 shown in FIG. 8 can comprise a first passage for passing the light beam from the light source 220 to the polygonal mirror 231 and a second passage for passing the light beam deflected by the polygonal mirror 231 toward the image forming optical system.

The sub-frame 440 includes a cover 433, which is removably connected to sidewall 431 to form a sealed structure.

At least one portion of the sub-frame 440 is preferably formed of a metal having high heat conductivity, such as aluminum, magnesium, foam aluminum, or zinc alloy, or a heat conductive plastic. When a material having high heat conductivity is used to form the sub-frame 440, the heat from the inside of the sub-frame 440 due to the polygonal mirror unit 230 is easily conducted to the first heat releasing member 450. Since foam aluminum has an excellent sound blocking characteristic, a sub-frame 440 formed of foam aluminum provide an excellent noise blocking effect as well.

The first heat releasing member 450 is disposed on the outer surface of the sub-frame 440 in order to transmit heat, preferably at a location farthest from the optical unit 500.

In FIG. 8, the first heat releasing member 450 is arranged on an outer surface 433 a of the cover 433 of the sub-frame 440 and on an outer surface 431 a of the sidewall 431 of the sub-frame 440, which is the farthest from the optical unit 500. Alternatively, the first heat releasing member 450 may be arranged on the cover 433 of the sub-frame 440 only, as shown in FIG. 9. In addition, the first heat releasing member 450 may be arranged on a portion of the sidewall 431 of the sub-frame 440 which is the farthest from the optical unit 500.

The first heat releasing member 450 is preferably formed of a ceramic. The first heat releasing member 450 converts heat generated from the inside of the sub-frame 440 into a far infrared ray and radiates the far infrared ray. Thus, the far infrared ray is radiated to the inside of the main frame 400 and does not cause an increase in the temperature of the optical unit 500.

Such a first heat releasing member 450 can be formed by coating a material having excellent absorbing/radiating properties of a far infrared ray, such as a ceramic, to a predetermined location on the sub-frame 440. Ceramic has a characteristic of converting heat into a far infrared ray and radiating the far infrared ray, and a characteristic of absorbing the far infrared ray and converting the far infrared ray into heat. Accordingly, when the ceramic heat releasing member is used, heat can rapidly be radiated away in a desired direction without increasing the temperature inside of a specific space.

The far infrared ray radiation unit and the far infrared ray absorption unit are preferably formed to face each other to form a short heat releasing path for minimizing heat loss, in order to improve the heat releasing efficiency.

In other words, an optical scanning unit according to an embodiment of the present invention includes a second heat releasing member 470 on the inner surface of the main frame 400 to face the first heat releasing member 450, and a third heat releasing member 490 on the outer surface of the main frame 400 to correspond the second heat releasing member 470. Accordingly, the shortest heat releasing path is formed to minimize heat loss.

The second and third heat releasing members 470 and 490 are preferably formed of ceramic. The second and third heat releasing members 470 and 490 are preferably arranged on the inner and outer surfaces 413 a and 413 b of the cover 413 of the main frame 400 and on the inner and outer surfaces 411 a and 411 b of the sidewall 411 of the main frame 400 to correspond to the first heat releasing member 450, which is disposed on the cover 433 of the sub-frame 440 and the sidewall unit 431 of the sub-frame 440 facing away from the optical unit 500. In addition, the second and third heat releasing members 470 and 490 may be disposed only on the inner and outer surfaces 413 a and 413 b of the cover 413 of the main frame 400 corresponding to the first heat releasing member 450, which is formed on the cover 433 of the sub-frame 440 only, as shown in FIG. 9.

The second heat releasing member 470 converts the far infrared ray, radiated from the first heat releasing member 450 into heat. The heat converted by the second heat releasing member 470 is conducted to the third heat releasing member 490 through the main frame 400.

The third heat releasing member 490 coverts the heat, which is conducted through the main frame 400 into a far infrared ray and radiates the far infrared ray to the outside of the optical scanning unit.

The second and third heat releasing members 470 and 490 can be formed by coating a ceramic on a certain area of the inner and outer surfaces of the main frame 400.

Here, the far infrared ray is transmitted at high speed, since the far infrared ray is not transmitted by convection or conduction. Thus the heat generated from the polygonal mirror unit 230 can rapidly be released by using the first through third heat releasing members 450, 470, and 490 arranged on the sub-frame 440 and the main frame 400. Accordingly, the transmission of heat generated from the polygonal mirror unit 230 to the optical unit 500, which is sensitive to the changes in the temperature, can be efficiently prevented.

The locations and the areas for coating the ceramic, which forms the first through third heat releasing members 450, 470, and 490, can be determined based on the heat releasing efficiency and the layout around the optical scanning unit within the system to which the optical scanning unit is applied.

It should be understood that one or more of the first through third heat releasing members 450, 470, and 490 can be formed by applying a film type or paint type material having good absorbing/radiating characteristics of far infrared rays. Also, one or more of the heat releasing member 450, 470, and 490 can be made of a material other than ceramic so long as the material has good absorbing/radiating characteristics.

As shown in FIG. 10, the optical scanning unit according to an embodiment of the present invention may include a barrier wall 80, which spatially separates the optical unit 500 from the polygonal mirror unit 230 and the sub-frame 440 in the main frame 400. The barrier wall 80 includes a passage 85 for processing the light beam. The passage 85 can be formed of an open space or a transparent window.

The barrier wall 80 helps to further minimize heat transmission from the beam deflector unit 230 to the optical unit 500.

The barrier wall 80 can be integrally molded with the bottom unit 415 and the sidewall 411 of the main frame 400.

The process for releasing heat generated by the beam deflector unit 230 of the optical scanning unit according to the embodiment of the present invention shown in FIG. 10 will now be described. The heat generated by the beam deflector unit 230 is absorbed by the sub-frame 440, which is preferably formed to prevent noise. The heat is converted into a far infrared ray by the first heat releasing member 450. The first heat releasing member 450 is preferably a ceramic material arranged on the outer surface of the sub-frame 440. The far infrared ray is radiated inside the optical scanning unit. The far infrared ray is absorbed by the second heat releasing member 470, which is also preferably made of a ceramic material. The second heat releasing member is arranged on the inner surface of the main frame 400 facing the first heat releasing member 450. The second heat releasing member 470 converts the far infrared ray into heat and transmits the heat through the main frame 400 by conduction. The heat conducted through the main frame 400 is converted into a far infrared ray by the third heat releasing member 490, which is preferably made of a ceramic material. The third heat releasing member is arranged on the outer surface of the main frame 400, and thus the far infrared ray is radiated to the outside of the optical scanning unit.

According to such an optical scanning unit, the shortest heat transmission path is formed to rapidly release heat generated by the beam deflector unit 230 to the outside of the optical scanning unit and to minimize heat transmission to the optical unit 500, which is sensitive to the changes in the temperature, in order to prevent a deterioration of optical performance.

In addition, the optical scanning unit according to an embodiment of the present invention radiates a far infrared ray. Thus, in a system to which the optical scanning unit according to an embodiment of the present invention is applied, the internal temperature is not increased.

Although exemplary layouts for the heat releasing members were described herein, those of ordinary skill in the art will recognize that the location for coating the ceramic can be changed based on the layouts of the inside of the optical scanning unit and the system to which the optical scanning unit is applied. Thus, the heat transmission path for releasing heat from the inside to the outside of the optical scanning unit can be changed according to design preference.

The application of the heat releasing technology using the radiation of a far infrared ray to the fixing unit and the optical scanning unit of an image forming apparatus has described above. However, heat releasing technology according to an embodiment of the invention can also be applied to various other units operating as a heat source unit in an image forming apparatus.

In other cases, the heat releasing technology using radiation of far infrared rays according to an embodiment of the present invention can be applied to various systems having a heat source unit, other than an image forming apparatus.

According to an embodiment of the present invention, since the heat releasing member, which converts heat into an far infrared ray and radiates the far infrared ray and vice versa, is used, heat can be efficiently released to the outside of the system without increasing the inner temperature of the system. Thus, heat can be released to the outside of the system at a low cost by arranging the heat releasing members at predetermined locations of the system without changing the structure of the system.

In addition, far infrared rays, which are safe to human bodies are radiated to the outside of the system, rather than heat or hot air. Thus, the system can be applied to produce an energy efficient and safe product.

Such a heat releasing technology is applied to at least one of the optical scanning unit, a fixing unit, and an electro-photographic image forming apparatus employing the same. The optical characteristics and the quality of images can be maintained by minimizing the increase of the inner temperature of the unit and efficiently releasing the heat to the outside of the unit.

Furthermore, the optical scanning unit to which the heat releasing technology according to an embodiment of the present invention is applied can generate higher heat releasing efficiency than a conventional optical scanning unit using heat releasing fins (a heat sink), and can be manufactured at a low price and in a small size.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims. 

1. A system comprising: a heat source unit; and a first heat releasing member arranged on the heat source unit or at a location near the heat source unit, to convert heat into a far infrared ray and radiate the far infrared ray.
 2. The system of claim 1, further comprising a housing containing the heat source unit, wherein an air layer is disposed between the housing and the heat source unit, or the heat source unit contacts the housing.
 3. The system of claim 2, further comprising a second heat releasing member arranged on an inner wall of the housing to convert the far infrared ray radiated from the first heat releasing member, into heat.
 4. The system of claim 3, further comprising a third heat releasing member arranged on an outer wall of the housing to convert heat conducted through the housing into a far infrared ray and to radiate the far infrared ray to the outside.
 5. The system of claim 4, wherein the third heat releasing member is formed of a ceramic.
 6. The system of claim 3, wherein the second heat releasing member is formed of a ceramic.
 7. The system of claim 2, further comprising a fourth heat releasing member arranged on an outer wall of the housing near the heat source unit to convert heat generated by the heat source unit and conducted through the housing into a far infrared ray and to radiate the far infrared ray.
 8. The system of claim 7, wherein the fourth heat releasing member is formed of a ceramic.
 9. The system of claim 1, wherein the first heat releasing member is formed of a ceramic.
 10. The system of claim 1, wherein the system is any one of an optical scanning unit, an image forming apparatus having the optical scanning unit, an image forming apparatus having a fixing unit, and an image forming apparatus having the optical scanning unit and the fixing unit.
 11. An optical scanning unit comprising: a beam deflector unit including a beam deflector for deflecting and scanning a light beam and a driving motor for rotating the beam deflector at a high speed; an optical unit including a light source and an image forming optical system for forming images from the deflected light beam, which is input from the light source to the beam deflector and scanned by the beam deflector unit; a main frame containing the beam deflector unit and the optical unit; a sub-frame surrounding the beam deflector unit to reduce noise generated by the beam deflector unit in the main frame and having a passage for passing the light beam between the beam deflector unit and the optical unit; and a first heat releasing member arranged on an outer surface of the sub-frameto convert heat generated in the sub-frame into a far infrared ray and radiate the far infrared ray:
 12. The optical scanning unit of claim 11 further comprising: a second heat releasing member arranged on an inner surface of the main frame to convert the far infrared ray radiated to the inside of the main frame by the first heat releasing member into heat; and a third heat releasing member arranged on an outer surface of the main frame to convert heat conducted through the main frame into a far infrared ray and radiate the far infrared ray to the outside.
 13. The optical scanning unit of claim 12, wherein the first through third heat releasing members are formed of a ceramic.
 14. The optical scanning unit of claim 11, further comprising a barrier wall within the main frame to spatially separate the optical unit from the beam deflector unit and the sub-frame, the barrier wall having a passage for passing the light beam.
 15. The optical scanning unit of claim 11, where at least one portion of at least one of the main frame and the sub-frame is formed of a heat conductive plastic having high heat conductivity. 